December 06, 2008

Smart people have better sperm

Intelligence doi:10.1016/j.intell.2008.11.001

Intelligence and semen quality are positively correlated

Rosalind Arden et al.

Abstract

Human cognitive abilities inter-correlate to form a positive matrix, from which a large first factor, called ‘Spearman's g’ or general intelligence, can be extracted. General intelligence itself is correlated with many important health outcomes including cardio-vascular function and longevity. However, the important evolutionary question of whether intelligence is a fitness-related trait has not been tested directly, let alone answered. If the correlations among cognitive abilities are part of a larger matrix of positive associations among fitness-related traits, then intelligence ought to correlate with seemingly unrelated traits that affect fitness—such as semen quality. We found significant positive correlations between intelligence and 3 key indices of semen quality: log sperm concentration (r = .15, p = .002), log sperm count (r = .19, p less than .001), and sperm motility (r = .14, p = .002) in a large sample of US Army Veterans. None was mediated by age, body mass index, days of sexual abstinence, service in Vietnam, or use of alcohol, tobacco, marijuana, or hard drugs. These results suggest that a phenotype-wide fitness factor may contribute to the association between intelligence and health. Clarifying whether a fitness factor exists is important theoretically for understanding the genomic architecture of fitness-related traits, and practically for understanding patterns of human physical and psychological health.

3 comments:

General intelligence itself is correlated with many important health outcomes including cardio-vascular function and longevity.

I must admit I get irritated when I read self-serving scientific articles on how "attractive" smart men are, how on average they are "healthier," how on average they have all of these positive qualities which at first glance seem unrelated to intelligence.

I work out, I practice cardio several times a week, I eat healthy (usually), and I suppose this may be related to my IQ, but these "studies" are irrelevant to the daily experience of your average "smart" person.*

Where I work (I don't know about your situation), the fittest people are typically at the bottom of the hierarchy (I'm the only manager who works out regularly, actually). The more intelligent guys, the (White) white-collar guys, typically have bellies (my CEO is obese). This does not mean they will die younger, since their wealth and intelligence will allow them to have better health care...

When these studies mention correlations, which I don't doubt are real, their strength may be exaggerated due to the biases of the scientist or interpreter of the study.

If intelligence in and of itself were so wonderful, so SEXY, so beneficial for the purposes of attracting a mate, as these "studies" would have you believe, all of the hottest girls on college campuses would be dating the geeks in the science labs rather than the jocks and frat boys.**

My belief is that these claims are made by those who identify themselves (rightly or wrongly) as "intelligent," and would like to believe they vicariously possess all of the wonderful traits associated with it.

*Smart people are more likely to be vegetarians and to understand the implications of behavior on health. Still, generalizations regarding intelligence and health require much more caution than we see here.

**I believe the jock with an above-average (not exceptional) IQ will have an edge over the dull jock, although both may do much better than the guy who spends an inordinate amount of time in the science or computer lab. This is partly where some "correlations" come in to play.

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